Gastric and esophageal intramucosal Pco2 (PiCO2) during endotoxemia -: Assessment of raw PiCO2 and Pco2 gradients as indicators of hypoperfusion in a canine model of septic shock

Study objectives: To validate capnometric recirculating gas tonometry (CRGT) for continuously monitoring gut intramucosal PCO2, (PiCO(2)) in a septic shock model, and to compare gastric vs esophageal PCO2 vs intramucosal-arterial PCO2 gradients. Interventions: CRTG catheters were placed in the stomach and esophagus of six anesthetized dogs. A saline solution filled balloon tonometry (ST) catheter was also placed in the stomach. After equilibration, 3 mg/kg Escherichia coli lipopolysaccharide (LPS) was administered N. PiCO(2) measurements were made at 0, 45, and 90 min post-LPS by ST and continuously by CRGT. Results: Baseline PiCO(2) was 41.5+/-1.9 (+/-SE) in the stomach by CRGT, 38.0+/-1.0 by ST, and 43.0+/-4.4 mm Hg in the esophagus (p=not significant). Gastric PiCO(2) by CRGT increased to 47.0+/-2.4 mm Hg by 25 min post-LPS (p<0.05), whereas gastric (ST) and esophageal PiCO(2) increased significantly by 45 min post-LPS. Good agreement was observed between gastric CRGT and ST measurements (mean bias, 1.3 mm Hg). The PiCO(2)-PaCO2 gradient increased post-LPS, but was significant: only for gastric CRGT measurements 90 min post-LPS infusion. Conclusion: CRGT provided continuous gastric PiCO(2) measurements that were in close agreement with ST but detected changes earlier than the conventional technique. Continuous esophageal PiCO(2) represents a valid alternative for assessing gastric PiCO(2).